Luffing crane

ABSTRACT

The crane boom is hinged to a frame on which is mounted a winch operating the boom through a pulley tackle. The fixed pulleys of the boom tackle are mounted on the crane frame and the movable pulleys thereof are linked to the boom head. The boom tackle has auxiliary pulleys mounted on symmetrically positioned brackets pivoted to the crane frame parallel to the boom luffing plane. The rope is reeved so that its parts connecting the movable and fixed pulleys run parallel to the boom luffing plane and the auxiliary pulleys are each connected to the movable pulleys by the same number of rope parts. Another winch mounted on the frame raises and lowers the load. The drums of both winches are kinematically interconnected so that they simultaneously rotate in opposite directions, whereby the boom is elevated while the load is lowered. Thus, the load is moved in a true horizontal path while the reach of the crane boom is varied.

United States Patent 1191 Glushko et al.

[ Aug. 13,1974

15 1 LUFFING CRANE [76] Inventors: Mikhail F edorovich Glushko,

prospekt Schevchemko 15/5, k.v. 17; Ilia Fedorovich Pakhomov, ulitsa Lenina 44/46 k.v. 55, both of Odessa, USSR.

[22] Filed: Dec. 20, 1972 [21] Appl. No.: 316,708

[52] US. Cl. 212/3, 212/58 R [51] Int. Cl. B66c 23/12 [58] Field of Search 212/3, 58 R; 254/139, 139.1, 254/188 [56] References Cited UNITED STATES PATENTS 3,286,851 11/1966 Sperg 212/3 3,486,635 12/1969 Thomson 212/58 R Primary Examiner-Richard A. Schacher Assistant Examiner-Jeffrey V. Nase Attorney, Agent, or Firm-Holman & Stern [5 7] ABSTRACT The crane boom is hinged to a frame on which is mounted a winch operating the boom through a pulley tackle. The fixed pulleys of the boom tackle are mounted on the crane frame and the movable pulleys thereof are linked to the boom head. The boom tackle has auxiliary pulleys mounted on symmetrically positioned brackets pivoted to the crane frame parallel to the boom luffing plane. The rope is reeved so that its parts connecting the movable and fixed pulleys run parallel to the boom luffing plane and the auxiliary pulleys are each connected to the movable pulleys by the same number of rope parts. Another winch mounted on the frame raises and lowers the load. The drums of both winches are kinematically interconnected so that they simultaneously rotate in opposite directions, whereby the boom is elevated while the load is lowered. Thus, the load is moved in a true horizontal path while the reach of the crane boom is varied.

2 Claims, 3 Drawing Figures PATENIEB AUG 1 31914 SHEET 2 or 3 /l/////// llll/ll PATENIEU mm 3:914

SHEET 3 0F 3 f lW-W LUFFING CRANE BACKGROUND OF THE INVENTION The invention relates generally to hoisting machines and more particularly, it relates to luffing cranes which are capable of moving the load horizontally by varying the reach of the boom.

Known in the art are cranes comprising a bed frame and a boom hinged thereto. The boom of such cranes is elevated and lowered through a pulley tackle, the fixed pulleys of which being attached-to the frame, whereas the movable pulleys are linked to the boom head. The rope of the pulley tackle is reeved so that the rope parts connecting the movable and fixed pulleys run parallel to the boom luffing plane, and the end of the rope is fastened to a cylindrical drum of a boom luffing winch mounted on the crane bed frame.

The bed frame also mounts a hoisting winch which operates a rope reeved in a hoisting pulley tackle.

The drums of the luffing and hoisting winches are interconnected kinematically in such a manner that the load is lowered while the boom is elevated, and raised while the boom is moved down refer, for example, to USSR Inventors Certificate No. 88,593, Class 35b, 304, 1950).

Such a design suffers materially from the disadvantage that the path of the load considerably veers off the horizontal. The cause of this disadvantage is that the cranes under discussion employ a boom pulley tackle of constant velocity ratio, which type of tackle fails to provide constancy of the vertical component of the boom head velocity a condition necessary to keep the path of the load horizontal while varying thereach of the boom.

Cranes of essentially the same type are known in which the drum of the boom winch is made in two parts connected to each other, one of these parts having a varying diameter. The boom winch winds the boom luffing rope and also the hoisting rope (refer, for example, to USSR Inventors Certificate No. 1,072,258, Class 35b, 204, 1956).

Such a design of the winch drum permits of maintaining the required relationship between the boom head elevating velocity and the load lowering velocity, whereby the load is moved horizontally while the reach of the boom is varied.

However, the maximum diameter of the drum under consideration is 4 to 6 times as large as its minimum diameter and the rope can be wound on the drum only in one layer. The resultant overall dimensions militate against the use of such a drum in a number of luffing cranes, especially where a long length of rope has to be wound. The employment of a varying-diameter drum is also impracticable in the cases where cranes use changeable booms of different length and the change of the boom calls for changing the drum.

SUMMARY OF THE INVENTION It is an object of the present invention to solve the problem of effecting truly horizontal movement of the load in luffing the crane boom.

It is a further object of the present invention to provide a simplified device for effecting horizontal movement of the load in luffing the crane boom and, at the same time, to enable a long length of rope to be wound while moving the load horizontally.

It is a still further object of the present invention to provide a relatively simple readjustment of the boom pulley tackle for the load to be moved horizontally with changeable booms of different length.

These and other objects are achieved in a luffing crane the boom of which is hinged to a frame mounted whereon is a winch which elevates and lowers the boom through a pulley tackle. The pulley tackle is essentially a system of movable and fixed pulleys. The fixed pulleys are attached to the crane frame and the movable pulleys are connected by a link to the boom head. The parts of the rope connecting the pulleys run parallel to the boom luffing plane. Another winch hoists and lowers the load through its own hoisting pulley tackle. The drums of the boom and hoisting winches are interconnected kinematically in such a manner that they rotate simultaneously in opposite directions whereby the boom is elevated while the load is lowered. The boom tackle is provided with auxiliary pulleys mounted on symmetrically located brackets which are pivoted to the crane frame, the axes of the bracket pivots being parallel to the boom luffing axis. The boom tackle rope is reeved so that the auxiliary pulleys are each connected with the movable pulleys by the same number of rope parts.

The design described above permits movement of the load in a truly horizontal path, with the fixed pulleys of the boom tackle being arbitrarily positioned on the crane frame, there being no need for complicated and costly varying-diameter drums.

Truly horizontal movement of the load can also be effected with the use of a wide range of changeable booms of different length and form.

The invention provides for a materially simplified device for horizontal movement of the load in luffing the crane boom and saves time required for adapting the crane for operation with the boom changed.

It is desirable that in the luffing crane which constitutes the present invention the movable pulleys of the boom tackle be mounted in a mutual axial alignment with a view of reducing the angularity of the rope in relation to the pulleys and thus extending rope life.

BRIEF DESCRIPTION OF THE DRAWING Now the invention will be described in detail with reference to the accompanying drawings in which:

FIG. 1 shows a general view of the luffing crane constructed in accordance with the invention.

FIG. 2 shows a general view of the boom tackle constructed in accordance with the invention (view taken in the direction of the arrow A in FIG. 1) and discloses the reeving of the rope in the boom tackle.

FIG. 3 shows a further embodiment of the boom tackle.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT According to the present invention, there is provided a luffing crane comprising a frame 1 (FIG. 1) which has a boom 2 hinged to it and mounts hoisting winch 3 and a boom luffing winch 4.

The luffing winch 4 operates the boom 2 through a pulley tackle which is essentially a system of movable pulleys 5 (FIGS. 1 and 2) and fixed pulleys 6, 7, 8, 9 and 10 (FIG. 2).

The movable pulleys 5 are connected by link 11 (FIGS. 1 and 2) to the head 12 of the boom 2, the fixed pulley 8 (FIG. 2) is pivoted on the crane frame 1, and the fixed, pulleys 9 and 10 are mounted on the crane frame 1 so that they rotate in a plane parallel to the boom luffing plane.

The auxiliary pulleys 6 and 7 are mounted on translationally motionless shafts 6a and 7a secured in brackets 13 and 14 which are mounted on the crane frame 1 by means of pivots l and 16, the axis 17 of the pivots being parallel to the boom luffing axis 18.

The boom tackle pulleys are reeved with the top 19 which is operated by the boom winch 4. The reeving is as follows:

From the boom winch 4 the rope 19 runs through the pulley 9, which is mounted on the crane frame 1, to the movable pulleys 5 and thence to the auxiliary fixed pulley 6. On passing round the pulley 6, the rope 19 runs back to the movable pulleys 5 and leads therefrom to the fixed pulley 8 and thence back to the movable pulleys 5. From there the rope 19 runs to the auxiliary fixed pulley 7, thence back to the movable pulleys 5 and therefrom to the fixed pulley through which the rope 19 returns to the drum 4a of the boom winch 4.

Although in the embodiment under consideration the rope 19 returns to the drum 4a, in another embodiment it may be fastened direct to the crane frame 1.

In the reeving described the parts of the rope 19 connecting the movable pulleys 5 with the fixed pulley 8 run parallel to the boom luffing plane, which, in particular, prevents the rope 18 from leaving the movable pulley 5 when the latter come within the area bounded by the axes of the pulleys 5, 6 and 7.

The movable pulleys 5 are connected to the auxiliary fixed pulleys 6 and 7 by the same number of parts of the rope 19, the rope parts being symmetrically inclined towards the boom luffing plane, whereby the axis of the movable pulleys 5 is positioned in the boom luffing plane when the boom tackle is at work.

According to the embodiment of the boom tackle shown in FIG. 3, the movable pulleys 5 and 5a are mounted in a common frame 20 on individual shafts located symmetrically in relation to the boom luffing plane. In this case the rope 19 is reeved as follows:

From the drum 4a of the boom winch 4 the rope 19 runs through the pulley 9, which is mounted on the crane frame 1, to the movable pulleys 5a and thence to the fixed pulley 7. On passing round the pulley 7, the rope 19 runs back to the pulleys 5a and thence to the fixed pulley 8. From the fixed pulley 8 the rope 19 runs to the movable pulleys 5, thence to the fixed pulley 6, thence back to the movable pulleys 5 and therefrom, via the pulley 10 mounted on the crane frame 1, the rope returns to the drum 4a of the boom winch or is fastened direct to the crane frame 1.

Apart from the reeving shown in FIGS. 2 and 3, the rope 19 may be reeved in any other way, provided that the fixed pulleys 6 and 7 are each connected with the movable pulleys 5 and 5a by the same number of rope parts.

The rope 21 of the hoisting winch 3 is passed over a pulley 22 mounted in the head 12 of the boom 2 and is further reeved in a hoisting tackle 23.

The drums 3a and 4a of the winches 3 and 4 respectively are kinematically interconnected by gears 24 and 25. The drums may also be interconnected through a differential, a planetary transmission or any other constant drive. To enable the hoisting winch 3 to operate independently, an arrangement may be provided in the form of a clutch or another device whereby the kinematic interconnection can be broken.

The luffing crane which constitutes the present invention operates as follows:

The drum 3a (FIG. 2) of the winch 3 and the drum 4a of the winch 4, being kinematically interconnected, simultaneously start rotating in opposite directions.

The drum 4a of the winch 4 winds the rope 19, which, running over the pulleys 5, 6, 7, 8, 9 and 10 pulls the movable pulleys 5. This pull ,is transmitted to the head 12 of the boom 2 through the link 11, which produces a luffing motion of the boom 2, whereas the rope 21 commences to unwind from the drum 3a of the winch 3, whereby the load is lowered relatively to the head 12 of the boom 2.

As the movable pulleys 5 are pulled towards the fixed pulleys 6, 7 and 8, a gradual change occurs in the angle of the parts of the rope 19 which connect the movable pulleys 5 with the fixed pulleys 6 and 7. The velocity ratio of the boom tackle and the speed at which the movable pulleys come towards the fixed ones change accordingly. This, in turn, causes a corresponding change in the elevation speed of the boom head 12.

These changes are so correlated that at any given instant the elevation speed of the head 12 of the boom 2 is equal to the lowering speed of the load. Thus, the load is moved horizontally while the reach of the boom 2 is varied.

When the boom 2 is lowered, the rope 19 is unwound from the drum 4a of the winch 4, whilst the rope 21 is wound on the drum 3a of the winch 3, whereby the load is raised. Under these conditions, again, the path of the load remains horizontal while the reach of the boom 2 is varied.

With the movable pulleys-5 pulled towards the fixed pulleys so that the reach of the boom 2 is at a minimum; the axis of said pulleys 5 may become located inside the area bounded by a line passing through the axes of the pulleys 6, 7 and 8. This position corresponds to the minimum velocity ratio of the boom tackle.

The embodiment of the luffing crane depicted in FIG. 3 operates essentially in the same way, except that the rope 19, when running over the movable pulleys 5 and 5a and the fixed pulleys 6 and 7 to pull up the movable pulley frame 20, inclines to the boom tackle pulley plane at a lesser angle than in the embodiment shown in FIG. 2, which materially lengthens rope life.

The boom tackle of variable velocity ratio, constructed according to the invention, can be used in luffing cranes of the self-propelled, tower, gantry, deck, floating and any other type, equipped with a straight, bent or articulated boom.

What is claimed is:

1. A luffing crane comprising: a crane frame; a boom being hinged to said frame; a pulley tackle; a luffing winch being mounted on said frame and operating said boom through said pulley tackle, said pulley tackle being composed of fixed and movable pulleys, said fixed pulleys being mounted on said frame and said movable pulleys being connected to the boom head by a link; symmetrically positioned brackets; auxiliary boom tackle pulleys being mounted on said symmetrically positioned brackets; pivots connecting said brackets to said frame parallel to the boom luffing axis; a rope reeved in said boom tackle pulleys so that the rope parts connecting said movable and fixed pulleys run drums being provided in said luffing and hoisting 5 winches and kinematically interconnected so that said winches rotate simultaneously in opposite direction,

whereby the boom is elevated while the load is lowered.

2. A luffing crane as claimed in claim 1, in which said movable pulleys of the boom tackle are positioned in mutual axial alignment. 

1. A luffing crane comprising: a crane frame; a boom being hinged to said frame; a pulley tackle; a luffing winch being mounted on said frame and operating said boom through said pulley tackle, said pulley tackle being composed of fixed and movable pulleys, said fixed pulleys being mounted on said frame and said movable pulleys being connected to the boom head by a link; symmetrically positioned brackets; auxiliary boom tackle pulleys being mounted on said symmetrically positioned brackets; pivots connecting said brackets to said frame parallel to the boom luffing axis; a rope reeved in said boom tackle pulleys so that the rope parts connecting said movable and fixed pulleys run parallel to the boom luffing plane, said auxiliary pulleys being each connected to said movable pulleys by the same number of rope parts; a hoisting winch with its own pulley tackle to raise and lower the load; and drums being provided in said luffing and hoisting winches and kinematically interconnected so that said winches rotate simultaneously in opposite direction, whereby the boom is elevated while the load is lowered.
 2. A luffing crane as claimed in claim 1, in which said movable pulleys of the boom tackle are positioned in mutual axial alignment. 